The invention relates to a device for the determination of dry substance of specimens with microwave heating and with a balance. The balance scale is located within the microwave heating area.
Devices of this type for the determination of dry substance are known e.g. from U.S. Pat. No. 3,909,598 or Japanese patent 51-136-489.
The use of microwave heating has the advantages over infrared radiant heating and direct heating in that a uniform heating of the specimens takes place and that only a relatively slight excess temperature is achieved during the drying process. The lower drying temperature prevents to a large extent a physical and chemical change of the specimens. Volatile substances which volatize at higher temperatures in addition to the water from the specimen and falsify the measured moisture value remain in the material at rather low temperatures. Moreover, the drying speed is greater for many specimens than in traditional heating methods.
However, the known devices for the determination of dry substance with microwave heating have the disadvantage that considerable design expenses are necessary in order to maintain the field strength of the microwave heating so constant over the entire surface of the specimen that a uniform drying is achieved.
The invention has the object of detailing a device for the determination of dry substance which permits a more uniform drying of the specimen and also further increases the number of specimens which can be measured during a certain period of time.